Demi Lovato's tattoo of a pair of lips, which has been dubbed the "vagina" tattoo, has now been replaced with a rose (see below). Image: Getty.

Here's what goes down when you talk trash about Demi Lovato, people.

Here's what goes down when you talk trash about Demi Lovato, people.

The 22-year-old has issued a stern response to tattoo artist Ashley McMullen, who slammed the pop star on Twitter for covering up the infamous "vagina" tattoo she gave her…and called out Demi's "drunk ass" behaviour, including "pissing all over our toilet seat".

Demi was not amused. Take a look at her epic takedown on TwitLonger:

Image: TwitLonger.

That is what you call "sass", FIXers. The former Disney teen star's feud with Ashley kicked off when Demi shared an Instagram photo of her lips tattoo covered up with a rose.

Image: Instagram

"Cool post @ddlovato, thanks for getting the tattoo covered up I did for free that you specifically asked for," Ashley tweeted. "Not to mention you didn't even have the courtesy to offer me any money in the first place.

"You pissed all over our toilet seat and you made a fool of yourself. What a shame that people look up to you. The tattoo you covered it with kinda sucks too. Looks like you might forever be a goon. #demilovato #scumbag #turd #claimstobesober #drankallthebeer #peepeetoiletseat #yousuck."

Ashley also said Demi acted "like a full-time slob" and never thanked her for dealing "with your drunk ass".

Demi initially responded with some Twitter emojis…but she obviously had a bee in her bonnet she needed to let out!